Actually, this is one area I had not thought about.
CalendarBudget currently has only 1 currency – depending on your browser local. If you are in a European locale, CalendarBudget shows the Euro symbol, If you are in UK, it shows pound symbol. Otherwise, it shows in the regular dollar symbol, but in the end, its just showing a symbol, there is no conversion happening.
I think the demand for this would be pretty low, but it may be useful for some. This one will go one the long-term wish list I think once higher priority things are taken care of. Once I get a few more wishlist features taken down, I’ll update the feature poll and let the voting direct development.